1. Field of the Invention
The present invention relates to an airbag apparatus for the protection of occupants.
Priority is claimed on Japanese Patent Application No. 2006-109621 filed Apr. 12, 2006, Japanese Patent Application No. 2006-109622 filed Apr. 12, 2006, and Japanese Patent Application No. 2007-6792 filed Jan. 16, 2007, the entire contents of which are incorporated herein by reference.
2. Description of the Related Art
In some airbag apparatuses which deploy an airbag in the interior of a vehicle with the gas supplied from an inflator to restrain an occupant at the time of collision of a vehicle, a vent hole is provided, in order to prevent the internal pressure of the airbag from rising excessively, and this vent hole opens during deployment of the airbag.
Also, in some airbag apparatuses, in order to control the volume expansion and internal pressure of an airbag, rupture joining parts which are ruptured during deployment are provided in advance in the airbag, and the volume of the airbag is increased gradually by the rupture of the rupture joining parts.
For example, JP-A-2005-199987 discloses an airbag apparatus in which ends of a vent hole cover to close a vent hole are joined to an airbag by rupture joining parts, and when the rupture joining parts are ruptured at the time of deployment of the airbag, the vent hole cover deviates from the vent hole to open the vent hole.
In this case, it is necessary to prevent the position of the vent hole cover from deviating during the deployment of the airbag before the rupture joining parts are ruptured, and to prevent the vent hole from opening. In connection with this matter, JP-A-2005-199987 discloses sewing the vent hole cover to the airbag in the vicinity of the vent hole.
However, since the conventional techniques of preventing the positional deviation of the vent hole cover increase the sewing parts and lower productivity, there is a need for improvement.
Also, since it takes time and effort to arrange the vent hole cover in the manufacture of an airbag, there is another need for improvement.